The present invention relates to an under trimming device for a multi-needle sewing machine, and more particularly to an under trimming device which effectively prevents parts of the under trimming device from solliding and/or interfering with the looper, which moves horizontally in the sewing operation, of the sewing machine while it enables the thread used in sewing to be temporarily sucked and clamped after the thread was cut and then be used in the next sewing Operation.
Multi-needle sewing machines are now widely used in private homes and factories. A multi-needle sewing machine of this kind generally has multiple sewing needles above a needle plate of the sewing machine to carry multiple needle threads while there is only one looper under the needle plate to carry a single looper thread. Since the sewing principle and needle movement of a sewing machine are not the subject of the present invention, they are not discussed herein. What the present invention wants to discuss is an under trimming means of the conventional multi-needle sewing machine used to cue the thread after the completion of one sewing operation wherein the cut looper thread has to be caught so that the next sewing operation can be started. Taiwanese Utility Model Application No. 75288507 entitled "An Under Trimming Device for A Cylindrical Sewing Machine" discloses an under trimming device for a multi-needle sewing machine. As shown in FIGS. 1 to 5 and 9 of the Taiwanese Utility Model Application No. 75288507, a linkage 30 is utilized to pull a cutting means 2 of the under trimming device so that the cutting means 2 moves in a direction shown in FIG. 9 to catch, cut, and clamp a looper thread 61, as shown in FIGS. 4 and 5. After the completion of one sewing operation, the looper thread 6 is then clamped between a plate 35 and a catcher 13 to facilitate the next sewing operation. There are at least two drawbacks in the Taiwanese Utility Model Application No. 75288507;
1. The catcher 3 swings in a curve Crack and is therefore easily collides with the looper and hence is damaged. PA1 2. The catcher 13 can not be too far away from the needle place to ensure the looper thread to be clamped securely. Besides, if the catcher 13 is too far away from the needle place, the free end of the looper thread after being cut will be too long for the next sewing operation. Instead, the catcher 13 has to be close enough to the needle plate without interfering the looper. The applicant developed an under trimming device for a multi-needle sewing machine to eliminate the drawbacks that exist in the conventional multi-needle sewing machine.